Method and apparatus for electrically treating fluids



Dec. 5, l1944. 'HQ woLFE l 4 v 2,364,118

METHOD ANB APPARATUS Fon ELECTRIGALLY TREATING FLUIns Filed Aplfil 5, 1939V /A/ Ven/TOR as r ' sarily equipotential surfaces.

Passed Dec. s, 1944 oFFlcE- METHOD AND-APPARATUS FOR ELECTRI- CALLY'TBEATING FLUIDS 4 Halley Wolfe, Los Angeles, Calif., assigner. by meine assignments, to Petrolite Corporation, Ltd., Wilmington, Del., a corporation o! Dela- Applicants April s, 193s. serial No. `wenn (ci. :o4-iss) Claims.

This invention relates to electrical treatment of fluids and, more particularly, to a method and apparatus for electrically resolving emulsions of water and oil into their constituent phases.

The treatment of water-in-oil emulsions by high-tension alternating fields has found wide by the emulsion, the voltage gradient that can l be applied is influenced by the fact that chains of water particles are formed between the electrodes, thus decreasing the effective length of insulating oil in the gap and resulting in dielectric breakdown short-circuiting, and consequent high currents. An occasional breakdown can be tolerated but, if the occurrence becomes too frequent, the power consumed becomes excessive, and, what is worse from the standpoint of treats ment, the average voltage between the electrodes usually drops due to regulation in the transformer-choke coil combination.

It is an object of the present invention to provide a method and apparatus for the electric treatment of water-in-oil emulsions in which the desired potential gradient is substantially mai'ntained throughout `all parts 'of the oil, irrespective of the condition of the emulsion or the variation of effective length of the dielectric oil in the inter-electrode gap due to local formation of conducting chains and the like. Itis, furthermore, an object of the invention to provide treatment of the kind described in which high gradients may be maintained in the oil without dielectric breakdown, short-circuiting, excessive current consumption, and the like, by providing electrode orbounding surfaces which are not neces- `in the field, whereby, withdue reference to the respective thicknesses, specific resistances and specific capacitive reactances of the dielectric and emulsion, vand the frequency of the limposed potential, the major portion of the voltage drop between the electrodes is taken up by the interposed dielectric, and only a minor portion thereof is imposed across the emulsion. By this means, major variations in the effective insulating thickness of the oil, such as may be caused by the formation of 'conducting chains, produce only.

relatively minor variations in the gradient in said oil. In effect, the potential dinerence across the emulsion layer at any given point is maintained substantially proportional to the effective dielectric thickness of the oil included, in the emulsion at that point and, hence, the desired optimum gradient can be maintained in all other parts of the oil without dielectric breakdown, the dielectric surface bounding one side of the emulsion layer being non-conducting and, hence, not necessarily equipotential.

It is, accordingly, an object of the present in@ vention to providefor the treatment of an emulsion as a layer in an inter-electrode space in series with an inter-electrode dielectric layer, the dielectric layer being arranged to take up a major portion of the potential diieren'cebetween the electrodes.

It is, furthermore, an object of the invention to provide a method and apparatus for the application of a potential difference across a layer of emulsion which varies locally according to the local dielectric thickness of the layer, the layer being bounded on one side by a non-equipotential surface.

' ence to a surface of high surface resistivity,

which may or may not be equipotential under ideal `conditions in which the emulsion is everywhere uniform, but which becomes a non-equipotential surface under conditions of local electric breakdown of the emulsion, the variations in the potential of the surface arising from such a local breakdown being restricted to that area of the surface in the immediate vicinity of the breakdown.

In accordance With my invention, I prefer to use alternating fields of high frequency such that the capacitive reactance of the emulsion layer becomes small with respect to its resistance,

whereby the relative voltage `drops across the interposed dielectric and the emulsion layer apportion themselves according to the respective Y capacitive reactances, and whereby the dielectric may be suitably chosen on the basis of its specific inductive capacity.

It is, accordingly, an object of the present invennen to met 'an emulsion layer with alternat- -ing fields of lsuch frequency that the capacitive reac lce ofthe emulsion layer is small with respect its resistance. It is, furthermore. an object to impress such a field across a space containing a dielectric layer whose capacitive reactance is atleast equal to that, of the emulsion layer. whereby the maior portion of the voltage drop is taken up by the dielectric layer and only a minor portion of the voltage drop is impressed across the emulsion layer.

In accordance with my invention, I may also provide that the electrode in contact with the emulsion layer has a water surface, i. e., the

' electrode may be formed of a `conducting body of water, or a water-wet septum, or similar wet material, such that the droplets of water in the emulsion being treated may co'alesce directly with said body of water. as well as with each other, or such that the partially coalesced masses of water in the oil may be removed directly from the oil without necessity for the usual settling process. Further objects and aspects of the invention will be apparent from the following discussion of Fig. 6 lis a section of another apparatus embodying myinvention.

Fig. 1 is intended to be illustrative of the formation of conducting chains of water droplets such as give rise to dielectric breakdown and short-circuiting in the usual type of treater. Conducting electrodes I0 and II for-m equipotential surfaces separated by a space containing the emulsion undergoing treatment. Dispersed throughout the oil are the emulsified water droplets which are represented by the greatly maglnified spheres I2. A-normal path for the electrostatic lines of force is shown by the dotted line Il. A chain of water droplets and of larger. partiallyv coalesced masses of water is shown by the dotted line Il. In each instance, the path is taken through the drops in order to penetrate the minimum possible thickness of oil and represents the path along which electric breakdown with high current flow would occur if the impressed voltage becomes tno high. It is seen that the thickness of the oil along the pathv Il is very much less than the thickness of the oil along the `path I3 and, for purposes of argument, the ratio may be taken as 1:10. When the impressed voltage is such that the oil along the path I4 is at incipient breakdown, the oil along the path AIl will be stressed to only one-tenth ofv its breakdown value. As a result. far less than the optimum treating is obtained along the path I3. In

other words, to prevent the breakdown of too` many paths, such as I4, the voltage gradient and. hence the coalescing forces in the main body of emulsion must be maintained far below the theoretically allowable value. In practice, I have found that it is rarely possible to impose on such a system a gradient more than one-third of the theoretically allowable value Iwithout obtaining undesirable short-circuiting and power consumption. v v

scans Fig. 2 illustrates a system embodying my invention. Il and Il are energized electrodes and interposed therebetween is a dielectric layer I1, leaving a layer Il which may be nlled with the emulsion, as illustrated. It is assumed that a high frequency potential is employed such that the impedance of the system is largely dependent on the capacitive reactances of the dielectric and the emulsion. The dielectric constant of the dielectric may be assumed to be about equal to the dielectric-constant of the oil or emulsion so that the voltage gradient is the same in both. and the dielectric layer I1 may be taken of such thickness that it is ten times the thickness of the layer space IB, whereby about of the voltage drop across the electrodessis taken up by the dielectric layer I1, and only about 10% is impressed across the emulsion layer. Assuming that the layer Il is filled with a dry oil corresponding to the continuous phase of the emulsion which is to be treated, and assuming that this dry oil =has a dielectric strength of about 25,000'volts per inch,

a total voltage may then be impressed across.-

the electrodes such that the gradient in the oil is about 22.000 volts per inch, andmanifestly no breakdown will result. Now, let a cluster or chain of water particles, such as illustrated along the dotted line I9, be formed in the oil layer,

as will happen when the dry oil is replaced with emulsion. The effective dielectric thickness of the oil along the path I8 may correspond to only one-tenth of the thickness of the layer I8. However, the reactance between the electrodes in this vicinity will have only dropped to 91% of its former value since the oil at m'ost can contribute but 10% of the total.. reactance, the remainder being afforded by the dielectric I1. With the same impressed voltage on the electrodes, the gradient through this region in the vicinity of the path I8 will have risen only to 22,000 divided by 0.91, or 24,200-volts, which is'still well below the breakdown gradient for the oil concerned.

namely, 25,000 volts. It will thus be seen that f the gradient maintained in the oil is substantially l constant irrespective of the condition of the emulsion or the formation or length of conducting chains. In effect, the potential difference across the layer I8 is at any given point automatically dropped to about the same degree that the thickness of the oil is reduced whenever chains or other conducting systems are set up in the emulsion. Thus, the potential difference impressed across the layer of the emulsion varies locally according to the local impedance of the emulsion and is always substantially proportional to the thickness ofthe oil included within the emulsion layer at that point.

Hence, no matter what the water content may be of the emulsion in the treating space, the oil phase thereof will not be stressed beyond the breakdown point. Furthermore, even though a chain broke down and became conducting, a high I,

current could not flow because no connection would thereby be established to the electrode Il,

the dielectric I1 still remaining a substantial barrier. Furthermore, the voltage gradient on the rest of the emulsion would be unaffected because the surface of the dielectric in contact with the emulsion is laterally non-conducting and may exist as a non-equipotential surface. Hence. full voltage may always be maintained across the electrodes and the desired treating gradient always maintained in the emulsion whereby optimum treating may be obtained under all conditions. Also, the power consumed by this system the conditions obtaining `in remains negligible under the varying conditions.

In the above explanation, certain simplifying assumptions have been made for clarifying the exposition, but it is not intended to limit the in- -vention to such simplified conditions. For examimpedance of the dielectric layer is greater than the impedance of the emulsion layer. Further more, it is unnecessary for the dielectric constant of the dielectric to be the same as the dielectric v constant of the oil for, while it is convenient for purposes of illustration to assume approximately the same voltagegradient in the dielectric and in the oil, it is not essential that they be the same. Also, the voltage gradient in the oil films .between the water droplets of a cluster would be vsomewhat higher than that calculated because of convergence of the lines of force, but this does not introduce substantial error into the argument.

At relatively high frequency, for example 100,000 to 200,000 cycles per second, the reacti media will be inversely proportional to their respective dielectric constants, and the potential difference across each layer will be equalto [the product of the gradient in the layer timesv the thickness of the layer. While, theoretically.

4the dielectric may be sufilciently characterized by its dielectric constant,` practically, it should also be chosen to have a dielectric strength such that no breakdown of the dielectric will occur slab 34 and the water-wet septum 3l. Emulsion is introduced into one end of the treating space 40 by means -of a pipe 4I,'and dry oil is removed from the other end ofthe space 40 by means of a pipe 42. A conducting electrode 43 is carried on top of the central 34. The plan view of the electrode 43 is shown y clearly in Fig. 4. and also the lateral extensions even though the emulsion becomes shortcircuiting, and its resistivity should be sufllciently high that it may be effectively regarded as an insulator or non-conductor.

Anothervadvantage vresident in my invention resides in the fact that water particles of any substantial size are removed directly from the relativelyv thin layer of emulsion by electrical attraction to the electrode 'without the necessity of settling. When a conducting particle comes near a charged plate, it becomes inductively charged, the charge being so distributed that there is a n et attractive force. Hence, the larger water particles, as they are formed inthe space'l of Fig. 2, will be drawn downwardly out of the oil and, thus, the settling process will be accelerated by the electrostatic attraction which, in many instances, will be several times as large as the gravitational forces. By making the 'electrodes I6 consist of a surface of a conducting body of water or a water-wet septum, the particles thus separated are immediately coalesced therewith and removed from the treating space i8.

Figs. 3 and 4 show sectional and planyiews of an apparatus embodying my invention. 30 is a tank containing a body of water 3| and having 'suitably a perforated metallic plate. 'Ihere is thus defined a layer or` zone of the treating space "between the central portion of the dielectric of the treating space 40, as defined by the separatinggasket 31, this gasket being shown in dotte'd lines in Fig. 4.- The electrode 43 is energized by high potential, high frequency current from a high frequency generator 44. The companion v electrode is formed by the water-wet septum 33 and mayv conveniently' be grounded by grounding tank 30. The septum 38, being water-wet, comprises a water surface 'bounding the electric field. The inter-electrode space is thus constituted by the treating layer 40 and the dielectric layer 34, and the relative thickness of these two layers is so adjusted that a sufciently large proportion of the voltage drop across the electrodes'is taken up in the dielectric so that variation in the impedance of the emulsion in the layer 40 will have relatively little eiect on the gradient in the oil phase inthe layer-40.

When the emulsion is introduced through the 4pipe 4| by means of a pump or other suitable device, itspreads out as a layer in the treating `space through the water-wet septum because of the repellent character of the latter for the oil and, furthermore, any hydrostatic head tending to force the .oil through theseptum may be counterbalanced by suitably adjustingthe back pressure in the water overflow pipe 32. The emulsion thus traverses the treating space 40 and is subiected to the treating action of the electric field. Very high gradients vmay be maintained in the emulsion in the layer 40, as hereinbefore explained, and the emulsion is thereby vquickly and eiectively treated, the small droplets coalescing into larger ones. These larger 4droplets settle, or are electrostatically attracted or otherwise migrate, to the water-wet septum and are there coalesced into the water-continuous phase represented by the body of water 3i. The dry oil substantially free from water particles is removed through the pipe 42, and water equivalent in volume to the separated water is removed through the water overflow pipe 32.

While the maintenance of suitablevimpedance ratios between the dielectric layer and the emulsion layer is the essence of my invention, this ration can be varied over rather wide`limits according to the character of the emulsion treated. the potentials employed, and the like. If it is desired to work with gradients in the oilwhich are near the dielectric breakdown value ofthe oil, then a dielectric having a substantially greater impedance than that of the oil should be employed so that the gradient in the oil may be very substantially stabilized so that no danger of breakdown will be present. On the other hand, if the emulsion is readily treated at gradients somewhat below the maximum allowable local changes in the impedance thereof,` such vasoccasioned by the formation of conducting chains and the like. As a rule, excessive ratios of dielectric impedance to emulsion impedance are not practical because they will require the portion of the dielectric slab v small potential thereacross will application of unduly high voltages across the electrodes in order to obtain the desired potential across the emulsion, or will require working with very thin layers of emulsion such that a set up the desired gradient.

While'substantially lessened sensitivity of the gradient through the 'oil may be obtained when the ratio of' dielectric impedance to emulsion im-` pedance is aslow as one, I find that, in practice, bestA results are obtained when working inthe ratio range of 3 to 8, although, in some instances, it may be desirable to go to ratios of l or 20, or even higher. As a rule, I find that excellent treating is obtained when the thickness of the emulsion layer is adjusted to give a gradient therein from 60 to 80% of the dielectric strength of the dry oil, although, in some instances, higher and lower gradients than correspond to this range may be advantageously employed to secure effective treating.

If desired, the4 electrode 43 of Fig. 3Vmay be covered by a layer 45 of transformer oil or other oil suitable for reducing corona effects.

In Fig. 5, an alternative embodiment of my invention is illustrated. Here, the energized electrode 50 is placed inside` and adjacent the bottom of a dielectric cup 5I.. The bottom of the dielectric cupprovides the inter-electrode dielectric layer of my invention. This cup is suitably .positioned in a container 52 filled with water up to the level 53. Emulsion is introduced by means of a pipe-54 and discharged at a point centrally under the electrode 50. The emulsion rises-until in contact with the bottom of the ,cup 5i and then spreads itself as a thin illm 55, the thickness of which is determined by the thickness of a dam ring 55, preferably constructed of material which is preferentially vwetted by oil, e. g., rubber. Treatment takes place in the film 55 substantially as described hereinbefore, the water at the level immediately below the lm 55 forming a water surface bounding the ileld. The dry oil flows under the dam 55 and passes upwardly to accumulate as a body of oil 51, suitably restrained by a cylindrical bar.-

rier 58. Treated oil is removed from the body l of oil 51 by means of a pipe 59, and the separated water is removed from the container 52 by means of a' pipe 59a. The apparatus shown in Fig. 5 is particularly adapted for use with high frequency current such that the relative voltage drops across the dielectric barrier and across the emulsion film 55 are adjustable according to the thickness and specic inductive capacities of the layers concerned to give the desired ratio of potential drops. The dielectric cup should have suiiicient dielectric strength to receive the entire applied potential, however, without being over-stressed.

In Fig. 5, the top of the electrode 50' maybe suitably protected against corona ei'iect by cover-- ing it with an oil having good dielectric properties, such as transformer oil.

Fig. 6 shows a vessel 10 having an emulsionA inletpipe 1l, oil withdrawal pipe 12, and water withdrawal pipe 13. the rupper or treating portion of which vessel is filled with a battery of electrodes 14 in dielectric cups. With regard to the dielectric cups-and electrodes there illustrated', the chief difference with regard to the cup and electrode assembly shown in Fig. 5 lies in the upturned edges of the electrodes 14 in Fig. 6. Alternate electrode assemblies are charged to opposite polarities by a source of high is rendered :,soans ypanneau 1l. and nenn are thus set up between the upturned edges of neighboring electrodes which are -effective in further treating the oil layer therebetween, the lower level of the oillayer l'iing preferably maintained below the electrodes I find thatv the apparatus and construction illustrated in Fig.v 8, as 'well asthat in Fig. 5, is advantageously employed in electrically treating emulsions generally, irrespective of the adjustment of relative voltage drops in dielectric and emulsion. It is, therefore, a further object of the invention to provide such novel arrangement of apparatus for electrically treating emulsions and, in particular, to provide a treating space containing a plurality of dielectric cups zont'aining electrodes of alternately opposite poari y.

It is to be understood that the above examples of methods and apparatus embodying my inven- Ytion are illustrative rather than limiting, and

lter-in-oil type with an electric field, comprising:

impressing a high tension high frequency alter-A nating-current potential across a tleld space defined by two electrodes; maintaining a layer of solid dielectric medium in one'portion ofsaid' inter-electrode field `space adjacent one electrode, said layer cooperating with the other of said electrodes in defining. a treating space comprising a zone of the inter-electrode space unoccupied by said layer of dielectric; and passing the emulsion to be treated through said treating space as a layer bridging said zone. said dielectric layer being characterized by such capacitive reactance at the frequency employed, relative to the capacitive reactance of the emulsion layer at the frequency employed,V that the portion of the impressed voltage absorbed by said dielectric layer is at least three times the portion absorbed by the emulsion layer, whereby the potential gradient in the oil of said emulsion substantially non-sensitive to changes in impedance of said emulsion, said potential being of sumciently high frequency that the capacitive reactance of the emulsion layer is small relative to its' resistance.

2. A process as in claim l in which the capacitive reactance of the dielectric layer is not greater than 20 times the v4capacitive reactance of the emulsion layer.

3. A process of treating oil-continuous emulsions, comprising: subjecting a layer of emulsion in series with a layer of solid dielectric having a non-conducting surface contacting said layer loi emulsion toV the action of a high potential high frequency alternating-current field, said dielectric layer beingcharacterized by a capacitive reactance at said high frequency which is at least three times and not greater than twenty times the capacitive reactance of said emulsion layer, whereby the voltage drop across said emul- Y thin layer in a space defined by a solid dielectric and a conducting electrode. said dielectric being positioned between said conducting electrode and a second electrode; land maintaining a high tension high frequency alternating-current field across said emulsion and dielectric by energization of said electrodes, said dielectric being of auch dimension and of such capacitive reactance at said high frequency as to absorb a portion of the potential drop in said field which is at least three times the portion absorbed by said emulsion layer.

6. .A process as in claim in which the conducting electrode is an electrode having a water surface bounding said space.

`'1. In combination in an apparatus for electrically treating water-in-oil emulsions: two

velectrodes defining an inter-electrode field space;

a solid dielectric layer positioned to extend e along said field space adjacent one electrode and defining with the other electrode boundary surfaces of an inter-electrode treating space, the

boundary surface of said dielectric being characterized by 'a high surface resistivity; means for introducing emulsion into said treating space; discharge means from said treating space for conducting electrically-treated emulsion constituents therefrom; and means for energizing said electrodes with high potential high frequency alternating current, said dielectric layer being characterized by such capacitive reactance at the high frequency employed relative to the capaci-` tive reactance of the emulsion between said boundary surfaces at the frequency employed that the voltage drop across the dielectric layer is at least three times the voltage across the emulsion in said treating space whereby a sub-` stantially constant gradient is maintained in the oil irrespective of variations in electric impedance of the emulsion and a minor fraction of the voltage drop is impressed across said emulsion, said minor fraction being suilicient to set up effective treating gradients in the oil of said emulsion.

8. In apparatus for treating emulsions of water in oil, the combination of: two spaced electrodes; means for impressing upon said elec-l trodes an alternating electromotiv'e force, wherei by an alternating electric field is set up and an l alternating current is caused to flow between said electrodes, the frequency of said electrometive force being suiciently high to result in the capacitive reactance 1 of a given body of said emulsion being small compared to the resistance of said body of emulsion; means to pass the emulsion to be treated between said electrodes in a stream of limited thickness; and a solid dielectric medium interposed in series with said emulsion stream between said electrodes, the thickness and specific inductive capacity of said solid dielectric medium at saidfrequency being such that the capacitive reactance of said solid dielectric medium encountered by said alternating current is at least three times the capacitive reactance of said emulsion stream.

9. A process for the separation of Water from an emulsion of the water-in-oil type by -use of an electrode means' having a water surface, which process includes the steps of: establishing a high-frequency alternating-current electric field to said water surface; disposing in said field a layer of solid dielectric material separated from said water surface by a small treating space con- 4 taining a` layer of the emulsion immediately adjacent said water surface, said layer of solid dielectric material having such capacitive reactance at the frequency employed. relative to the capacitive reactance of the emulsion layer at the frequency employed, that the portion of the impressed 4voltage absorbed by said, layer of solid dielectric material is at least three times the portion absorbed by the emulsion layer whereby said field acts to coalesce the water droplets of said emulsion and electrically attract those adjacent said water surface to bring the coalesced water droplets directly to said surface; and maintaining the water surface in substantially constant spacial relationship to the dielectric barrier.

10. In combination in an apparatus` for treat- .ing emulsions of the water-in-oil type by use of an electrode means having a horizontally dis- `posed water surface: a substantially horizontal electrode disposed above said Water surface; a source of high-potential, high-frequency, alterhating-current connected between said electrode l actance at the frequency employed, relative to the capacitive reactance of the emulsion layer at the frequency employed, that the .portion of the voltage impressed between said electrode and said water surface which is absorbed by said layer of solid dielectric material is at least three times the portionV absorbed by the emulsion being treated. whereby the potential gradient in the oil of said emulsion is rendered substantially non-sensitive to changes in impedance of said emulsion, said electric field acting to coalesce o the water droplets of said emulsion and electrically attract those adjacent said water surface tobring the coalesced water droplets into coalescing contact with said water surface; and means for withdrawingthe thus-collected water from a zone below said water surface.

\ ll. In combination in an apparatus for treat- .4 ing emulsions of the water-in-oil type: an upper electrode extending substantially horizontally; a lower electrode comprising a water-wet septum providing a Water-wet surface extending substantially horizontally; alternating potential means for energizing said electrodes to establish a field therebetween terminating at said waterwet surface; a layer of solid dielectric material in said field below said upper electrode and providing a lower surface. spaced from said waterwet surface of said septum to define an emulsion-treating space; means for delivering emulsion to said treating space to fill the zone between said lower surface of said dielectric layer l and said water-wet surface whereby said oil contacts said lower surface ofsaid layer of solid dielectric material to prevent water-wetting thereof and to maintain a high surface resistivity, said electric field acting to coalesce the water droplets of said emulsion and electrically attract those adjacent said water-wet surface to bring the coalesced water directly to said surface for movement through said water-wet septum said layer oi' solid dielectric material having sufficient dielectric strength to withstand without electrical breakdown the entire potential applied between said electrodes by said alternating potential means and being of such ca' pacitivereactance with respect tothe capaci- Ative rea'ctance of said emulsion as absorb aA portion of the potential between the electrodes which is'at least three time the portion absorbed by said emulsion; and means for removing water from a position below said septum.

12. In combination in an apparatus for treating emulsions or the water-in-oil type: a body of solid dielectric material providing upper land lower surfaces and disposed substantially horizontally: a nrst electrode adjacent said upper surface; a body of water providing a surface below said lower surface and cooperating therewith to form a treating space; means for introducing emulsion in an upward direction into the central portion of said treating space,. whereby said emulsion spreads outward and moves through said treating space; and means for maintaining an alternating potential diifereneeA as eans surface; a body of water below said lower surface: an annular dam 'extending downward from said lower surface to a positionbeneath the surface of said body of water to bound a treating space; means for introducing emulsion into said treating space to new toward said dam between said lower surface and said surface of said body of water; means for establishing an alternating potential difference between said electrode and said body of water of sumcient intensity tojcoalesce the dispersed water droplets of said emulsion.- the -coalesced droplets joining said body of water, the treated oil moving downwardbeneath said dam. said body of solid dielectric material providing eufilcient dielectric strength to withstandwithout electrical breakdown the entire potential applied by said lastnamed means' between said electrode and said body of water and being of such capacitive reactance with respect to the capacitive reactance of said emulsion as to absorb a portion of the potential difference Abetween the electrodes which is vat least three times the portion absorbed by said emulsion; and means for collecting the treated oil.

14. A combination as dened in claim '7, in

I which the ratio of the capacitive reactance of ing emulsions of the water-in-oil type a body of solid dielectric material providing upper and lowersurfaces and disposed substantially horizontally; a first electrode adiacent said upper vat said dielectric medium to the capacitive reactance of said. emulsion is from 3 to about 8.

l5. A combination' as denned in claim 8, in which the thickness of said stream of emulsion and the electromotive force impressed thereacross is such as to give a gradient therein from about Gil-80% of the dielectric strength of the oil of said emulsion. I

HALLEY WOLFE. 

